The long-term objective of the project is to understand how visual attention interacts with motion perception and visuo-motor systems to track the motion of target objects. The specific aims of the proposed research are: 1) to describe the mechanism that is used when visual attention tracks object movement; 2) to determine what factors cause errors in attentional tracking; and, 3) to investigate whether attentional tracking is critical for the active manipulation of objects and the perception of control. Behavioral and neuroimaging experiments are proposed to elucidate the cognitive structure and neural basis of attentional tracking. When visual attention is used to track objects, selection mechanisms must interact with perceptual systems coding motion trajectories and object positions. Our work has shown that noticing the change in position of an object constitutes a motion detection system that is dependent on visual attention. Proposed experiments will relate attentional tracking to this system. Specifically, we will compare spatial limits of position-dependent motion detection to the spatial resolution of attention. Also, we will measure brain activity with functional magnetic resonance imaging (fMRI) to determine if the same brain areas are involved in position-sensitive motion perception and attentional tracking. This project will also investigate why errors are made in attentional tracking. Evaluation of attentional tracking with displays containing different types of motion noise will test whether attentional tracking inappropriately integrates motion. Neuroimaging studies will measure brain activity in response to errors to determine if errors are caused by mistakes in coding motions or lapses in the continuity of attentional movements. The last series of experiments will investigate whether attentional tracking mediates the use of visual feedback for the perception of control during manipulation of an object. Proposed experiments will also test whether brain activity correlated with perceived control is coincident with activity related to attentional tracking or activity involved in intentionality. The intellectual contribution of this project will be a better understanding of how visual attention tracks objects, why it fails and how it is employed in the perception of control. This information will be valuable to a number of practical applications, such as human-machine interface design, as well as clinical issues, such as development of visual prosthesis and development of treatments for visual attention deficits.